<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no" />
    <title></title>
    <style type="text/css">
        *{
            margin: 0;
            padding: 0;
        }
        #box{
            width: 8rem;
            height: 8rem;
            border: 1px solid #000000;
        }
    </style>
</head>
<body>
<div id="box"></div>
</body>
<script type="text/javascript">
    var box = document.getElementById('box');

    //获取设备像素比
    var dpr = window.devicePixelRatio;
    //比例
    var scale = 1/dpr;

    //获取屏幕宽度 375
    var width = document.documentElement.clientWidth;

    //获取meta标签
    var metaNode = document.querySelector('meta[name="viewport"]')
    metaNode.setAttribute('content','width=device-width,initial-scale='+ scale +',user-scalable=no')

    //元素比例乘回来
    var htmlNode = document.querySelector('html');
    htmlNode.style.fontSize = width/16*dpr + 'px';

</script>
</html>
